How to build Visual Studio Code from sources behind a proxy?

Question

gulp.js

Hello.
Do not tell me what could be the error in the assembly of Visual Studio Code from the sources https://github.com/Microsoft/vscode ?
I collect under Windows.
Assembly description . At home, everything collects and runs without problems. At work it gives an error ( enlarge ):

The difference in the configuration is a corporate proxy at work, there is no proxy at home. I've never used gulp, so I can't be sure if the proxy is the problem.
The http_proxy and https_proxy system variables are set.
The proxy settings for npm are also set and all npm packages are downloaded through the proxy normally.